Non-digestible fat substitutes of low-caloric value

ABSTRACT

Low calorie food compositions containing fat-type organoleptic ingredients and non-fat ingredients, wherein natural fats and synthetic fat mimetics are blended in proportion to provide any predetermined amount of fat caloric value, said synthetic fat-type mimetic ingredients comprising esterified epoxide-extended polyols (EEEPs) of the formula P(OH) a+c  (EPO) n  (FE) b  where P is a polyol having a=2-8 primary hydroxyls, c=0-8 secondary and tertiary hydroxyls, a+c is in the range of 3-8, EPO is a C 3  -C 6  epoxide, FE is a fatty acid acyl moiety, n is the minimum epoxylation index average number having a value generally equal to or greater than a and is a number sufficient that greater than 95% of the primary hydroxyls of the polyol are converted to secondary or tertiary hydroxyls, and 2&lt;b≦a+c. The EEEP&#39;s have general use as non-digestable fat substitutes having non-caloric food values, good organoleptic characteristics (mouth feel), are substantially resistant to intestinal absorption, do not appreciably hydrolyze in the digestive tract, and have characteristics similar to vegetable oils and fats. Suitable polyols include sugars, glycerides or saccharides which are reacted (etherified) with C 3  -C 6  epoxides such as propylene oxide, butylene oxide, isobutylene oxide, pentene oxide, and the like to produce epoxide-extended polyols (EEPs) having an epoxylation index number, n, generally in the range of 2-8 and then acylated with C 8-24  fatty acids. Best mode examples are acylated propoxylated glycerol compound mixtures (APGs) which are resistant to pancreatic lipase in vitro, and feeding studies show them to be suitably resistant to overall digestion.

FIELD

This invention relates to esterified epoxide-extended polyols (EEEPs),methods of preparation thereof, and their use as non-digestible,non-caloric fat substitutes (fat mimetics) for cooking and in foodcompositions. The EEEPs have good organoleptic characteristics, haveacceptable levels of resistance to overall digestibility as measured byrat feeding studies. More particularly, the invention relates toacylated epoxylated glycerol compound mixtures (APGs) of the formula[P(OH)_(a+c) (EPO)_(n) (FE)_(b) ], where P is a polyol having a=2-8primary hydroxyls, and C=0-8 secondary plus tertiary hydroxyls, with a+cbeing in the range of 3-8, EPO is a C₃ -C₆ epoxide, FE is a fatty acidacyl moiety, n is the minimum epoxylation index average number having avalue generally equal to or greater than a and is a number sufficientthat greater than 95% of the primary hydroxyls of the polyol areconverted to secondary or tertiary hydroxyls, and 2<b≦a+c, which areresistant to hydrolysis by pancreatic lipase. The resultant EEEPs mayhave physical properties ranging from a liquid oil, through fats andgreases. They are useful in food formulations and cooking as they havegood mouth feel and characteristics similar to vegetable oils and fats.Being relatively non-absorbable, non-digestible, and non-toxic they maybe substituted for natural or processed oils and fats, but have lowcaloric value.

BACKGROUND

The accumulation of medical evidence in recent years regarding theadverse health implications of high fat diets, principally heartattacks, atheriosclerosis and overweight, has caused consumers to becomeextremely concerned about their diets. It is estimated that between70-80% of U.S. adult females follow a weight reducing diet at least oncea year. Men are also concerned about their weight and cholesterollevels. The concerns of both men and women have given rise to diet fads,diet drinks especially in the soft drink, wine and beer industry, andexercise programs and health clubs.

Common obesity is one of the most prevelant metabolic problems amongpeople today. Fats and oils are necessary for balanced nutrition.However, the average consumer simply consumes more than is needed forproper nutrition. Fat, at 9 calories per gram, as compared to 4 caloriesper gram for carbohydrates or proteins, is the most concentrated dietaryenergy form. It is estimated that fat constitutes about 40% of the totalcalories in the typical western diet. Fats are consumed directly inmeats, spreads, salad oils, and in natural produce such as nuts andavocados. Fats and oils are consumed as a result of absorption orincorporation in the foods during baking and frying. The vast increasein consumption of fast foods is a major contributor to the increase inthe amount of dietary fat since fast foods rely extensively on fryingprocesses employing fats and oils. In addition, the snack food industryuses large amounts of fats and oils in the production of potato chips,corn chips and other snack items. For example, in 1981 the USDAestimated approximately 12 billion pounds of fat and oil were used inedible products, predominately baking, frying fats, margarine, salad oiland/or cooking oil.

There is thus a clear indication that there is an enormous potentialhealth food market for a fat substitute or fat mimetic that is eitherentirely non-digestible, or has reduced caloric value. Manynutritionists believe that Americans typically rely on fats for toolarge a proportion of calories in their diet. The National ResearchCouncil, for example, has recommended that Americans reduce theproportion of their dietary calories coming from fats from 40% to atleast 30%. Replacement of fats in the diet with non-caloric substitutesis a more efficient way of reducing caloric intake than replacing sugaror carbohydrates because gram for gram, the substitution of non-caloricfat substitutes is more than twice as effective than reducingcarbohydrate content with such things as saccharine or Nutra-sweet.

One of the difficulties in eliminating fat from the diet is the factthat fats and oils are all-pervasive in food products. In part, this isbecause they play an important role in the organoleptic acceptability offood products. For a fat substitute to be acceptable, it must benon-digestible, that is, not hydrolyzed in the digestive tract. Inaddition, it should not be directly absorbed through the intestinalwall. While some types of fat substitutes may be non-digestible, theyare not of sufficiently high molecular weight to prevent them from beingabsorbed through the intestinal wall. The threshold molecular weight ofnon-absorbability for lipophilic molecules appears to be about 600.

In addition, the fat substitute must itself be non-toxic at high levelsof ingestion. It must contain no toxic residues or impurities. To theextent that a fat substitute may be partially hydrolyzed in thedigestive tract, any hydrolysis products must be non-toxic and/ormetabolizable. If metabolizable, they should have very low caloricvalue. In general, fat substitutes must be without any serious medicalside affects.

The fat substitutes must also have good organoleptic qualities of mouthfeel and have no taste. In addition, fat substitutes must haveappropriate physical properties for use in food compositions. That is,they should be liquids or solids depending on whether they are used asoil or shortening substitutes, and where used for cooking, must bethermally stable. While certain polysaccharide gums have been used asthickening agents, bulking agents or fillers in low-calorie foods, theycan give a product a "slimy" mouth feel and are unsuitable for cookingas they have no thermal stability.

Acceptable synthetic fats would be added in large quantities (30-60%) tosalad oils, cooking oils, margarines, butter blends, mayonnaise,shortenings and the like to create a new class of low-calorie products.While "low calorie" mayonnaise and salad dressings are presentlyavailable, the reduction in calories is achieved by increasing the watercontent with a corresponding loss in the organoleptically "rich" tasteof such products.

A current review of the field is found in a feature article entitled"Getting The Fat Out--Researchers Seek Substitutes For Full-Fat Fat"JAOCS, Vol. 63, No. 3, (March 1986) pp. 278-286, 288.

One prior art proposed fat, substitute is sucrose polyester (SPE) shownin U.S. Pat. Nos. 3,251,827 (Schell et al of Farben fabriken Bayer) and(Matson, et al. 1971) 3,600,186 and 3,963,699 (Rizzi, et al., 1976) ofProctor & Gamble. The SPEs are produced by the reaction of amonosaccharide, disaccharide or sugar alcohol having a minimum of fourhydroxyl groups with fatty acids having from 8-22 carbon atoms. It wasreported in "Chemical and Engineering News" (July 26, 1982, page 32)that incorporating SPE as a partial replacement of the fats in the dietsof ten obese patients dropped their caloric intake while satisfyingtheir perceived need for fats. An additional benefit was the lowering ofserum cholesterol, low density lipo-protein and triglycerides, all ofwhich have been implicated in artery hardening diseases. However, SPEhas the serious disadvantage of causing diarrhea, and plasma vitamin Aand vitamin E levels are decreased.

The process for production of SPE is basically a methanolysis followedby esterification and extraction. The SPE process requires long reactiontime with alternating additions of fresh transesterification catalystand excess methyl soybean fatty acid ester (RCO₂ Me). Temperaturecontrol is critical because sucrose will char at its melting point of185° C. Further, in order to solubilize sucrose in the esterificationsolution, it must be added slowly as a micron-sized powder (produced byreduction of sucrose crystals in a hammermill) to a solution of RCO₂ Mecontaining half as much alkali metal soap as sucrose. After the sucroseis partially esterified, excess RCO₂ Me is added and the mixture heatedat 145° C. for 8-12 hours. The fatty ester starting material, RCO₂ Me,is not made in a continous process. Rather, it is made in a batchprocess and must be washed with water to recover all the glycerol.Commercial cane sugar must be reduced to a consistency of fine talcumpowder, on the order of 50 microns or below in order to promote itsdissolution in the reaction solution. Two stage addition of RCO₂ Me isnecessary to prevent disproportionation to sucrose, which will char, andsucrose higher esters. For each pound of SPE made, one pound of RCO₂ Memust be cleaned up and recycled. Because a large excess of RCO₂ Me isused, the isolation of SPE is a complex process necessitatingliquid-liquid extractions at C with methanol or ethanol to removeunreacted RCO₂ Me. A final extraction with hexane and clay bleaching isnecessary to produce a light-colored product. The major yield lossoccurs during the purification process.

U.S. Pat. No. 3,251,827 discloses a preparation of SPE by means of asolvent-free interesterification using phenyl esters. However, phenol isliberated during the reaction. Since phenol is extremely toxic andcaustic, it contaminates the product and is very difficult to separate.Accordingly, this process did not prove satisfactory for synthesis ofSPEs for the food industry. U.S. Pat. No. 3,963,699 calls forsolvent-free transesterification involving heating a mixture of thepolyol containing four hydroxyls, fatty acid lower alkyl ester, andalkali metal fatty acid soap in presence of a basic catalyst to form ahomogenous melt, and subsequently adding to the reaction product of thatheated mixture excess fatty acid lower alkyl esters to obtain the SPE.

U.S. Pat. No. 4,034,083 also to Proctor and Gamble disclosesfortification of the SPEs with fat-soluble vitamins to formpharmaceutical compositions for treating or preventinghypercolesterolemia in animals, and for use in low calorie foods. Thismixture is required because eating SPE causes vitamin depletion as notedabove.

U S. Pat. No. 3,818,089 indicates that the C₁₂ -C₁₈ ether analogs ofglycerides, glycerine alkyl ethers are not digestible.

As shown in C. U. Werl et al, Food Cosmet. Toxicol., 9 (1971) p. 479,monopropylene glycol (MPG) can be ingested with no harmful effects. Itis metabolized by the same metabolic pathways used by carbohydrates. MPGis currently used as a humectant in shredded coconut and in moist cakemixes. Ethylene oxide and propylene oxide-based food additives, such aspropylene glycol mono-stearate, are recognized food additives, withallowable limits being prescribed by code.

Booth, A., and Gros, A., in a paper entitled Caloric Availability andDigestibility of New-Type Fats, Journal of the American Oil ChemistsSociety, Vol. 40, October 1963, pp. 551-553, disclose that in ratfeeding studies amylose palmitate, amylose stearate and amylose oleateare only 17-29% digested. A related prior paper of Gros, A., and Feuge,R., entitled Properties of the Fatty Acid Esters of Amylose, Journal ofthe American Oil Chemists Society, Vol. 39, Jan. 1962, pp. 19-24discloses that these esters do not have sharp melting points and areextremely viscous when melted. The densities were somewhat greater thanthose of corresponding free fatty acids and glycerides. While theinterest was for use as dip-type coatings in both foods and non-foods,no information appears to be available concerning the ability of thesecompounds to mimic sensory and functional properties of triglyceridefats in foods.

Mangold and Paltauf extensively reviewed ether lipids in their bookEther Lioids, Academic Press 1983. They report that trialkyl glycolshaving long alkyl chains are not hydrolyzed or absorbed when fed torats. These long chain trialkylated glycols are reportedly non-toxic anddo not interfere with absorption of fats and fat soluble vitamins.However, they are oxidized much more easily than normal fats havingcomparable acyl chains, so stability appears to be a problem. Further,these compounds are difficult and expensive to prepare.

Swift and Company Canadian Pat. No. 1,106,681 issued in 1981 relates todialkyl glycerol ethers which are absorbed only in small amounts whenfed to rats. Blends are said to exhibit the physical and organolepticproperties of conventional fats.

U.S. Pat. No. 2,962,419 discloses esters of neopentyl type alcohols suchas pentaerythritoltetracaprylate. The alcohols contain from 1-8 hydroxylradicals and include at least one neopentyl nucleus while the fattyacids contain at least four carbon atoms. They were shown to benon-hydrolyzable by pancreatic lipase. Rats fed with these esters hadlower levels of lipids in their serum. However, in demand feedingstudies, rats which received these neopentyl alcohol esters ate morefood than the control rats and thus there was no difference in weightgain among the two groups. Accordingly, it is possible that fat cravingis stimulated by these compounds rather than satisfied.

Retrofats are esters of fatty alcohols with tricarboxylic acids. It isreported that they are not hydrolyzed by pancreatic lipase and thus mayhave potential as non-absorbable fat substitutes. However, increasedstool bulk resulting from ingestion of the non-absorbable retrofats isreported to be a potential drawback.

Alkyl esters, such as dodecyl ester of 2,3-ditetradecyloxypropionic acidhave been suggested as a fat substitute but were found to be metabolizedand absorbed in vivo rat study experiments. The alkyl ester group wassplit off first, followed by the alkyl ether groups.

As reported in JACS, Vol. 8 (1958) pp. 6338 ff and JAOCS, Vol. 36 (1959)pp. 667 ff, the USDA has synthesized a number of diglyceride esters ofshort chain dibasic acids for potential application in foods. Distearinglyceride esters of dicarboxcylic acids were found to be poorly digestedand utilized by rats. Distearin adipate was almost completelynon-digested while adipostearin was only 58% digested in rat feedingtrials. In contrast, the oleostearin and dolein esters of dicarboxylicacids were more digestible and utilized. The symetrical diglycerideesters of fumaric, succinic and adipic acids are more viscous thancottonseed oil and coconut oil. These may have use as pan greases, slabdressings or surface coatings for foods.

U.S. Patent 3,579,548 to Procter and Gamble in 1971 discloses uses oftriglyceride esters of alpha-branched carboxylic acids as low caloriefats. These esters exhibited a coefficient of absorbability ranging fromabout 0-50 as compared to 90-100 for ordinary triglycerides. It ispostulated that the alpha-branched carboxylate structure prevents thecompounds from being hydrolyzed by pancreatic enzymes. Proposed uses areas fat replacements in salad oil, mayonnaise, margarine and dairyproducts.

Polyoxyethylene stearate is an emulsifying agent with fat likeproperties that yields only 4.2 kcal/gram when ingested. The molecule ishydrolyzed to stearic acid which is metabolizable, and topolyoxyethylenediol which is excreted unchanged. The use of fat-likeemulsifying agents as low calorie fat substitutes has been suggested inthe literature.

U.S. Pat. No. 3,337,595, issued to Nalco Chemical in 1967, discloses amethod of producing fatty acid esters of polyoxypropylated glycerol ofthe formula glycerol (propylene oxide)_(n) (fatty acids)_(m), which fromthe molecular weight values in the patent result in n=9-16 and m=1 or 2.These esters are disclosed to be useful for controlling, suppressingand/or preventing foaming of aqueous systems having foaming tendenciesin industrial processes. Illustrative types of aqueous systems arecellulosic suspensions involved in the manufacture of paper, sewagedisposal systems, detergent containing systems, saponin-containingsystems, protein containing systems and the like. 1,2-propylene oxide isadducted on glycerol to produce a polyoxypropylated glycerol (POG) witha molecular weight in the range of 600-1,000. Fatty acid esters areprepared by stoichiometric esterification of the POG with saturated orunsaturated alphatic monocarboxylic acids having chain lengths of 12-22carbons. The esterification process occurs in the range of 200-240° C.under a vacuum on the order of 30-50 mm mercury. Specific examples aredirected to stearic acid diesters of polyoxypropylated glycerol having amolecular weight of 700. An emulsifier is required in the anti-foamingformulations, the specific examples being directed to polyoxyethyleneglycol 400 di-oleate. The monocarboxylic acids used to form the diestersare those having C₁₂₋₂₂ carbons. There is no specific disclosure of atriester or of complete etherification with propylene oxide. There isalso no disclosure of the use of the diester compounds as fatsubstitutes in food products.

Gibson, U. H., and Quick, Q., in a paper entitled The Average MolecularStructure of Base-Catalyzed Low-Mole Adducts of Propylene Oxide toGlycerin, J. Applied Polymer Sci., Vol. 14 (1970) pp. 1059-1067 indicatethat with a molar ratio of glycerin (G) to propylene oxide (PO) of 1:3,63% of the adduct product will have all three hydroxyls propoxylated,with 1:4,92% are propoxylated, and with a ratio of 1:5 all the originalhydroxyls will be propoxylated.

It is clear that there is a great need in the art for improved fatsubstitutes that are easy to synthesize and do not have thedisadvantages of the prior art proposed compounds.

THE INVENTION Objects

It is among the objects of this invention to provide improvednon-digestible fat substitutes comprising esterified epoxide-extendedpolyols (EEEPs) which may be used alone as cooking oils, fats or waxes,or as part of food compositions, as a partial or total substitute forfats or oils.

It is another object of this invention to provide a non-digestible,non-absorbable, non-caloric fat substitute or fat mimetic useful in foodcompositions or for the preparation of food.

Another object of this invention is to provide improved, substantiallynon-digestible fat substitutes or partial substitutes, of theepoxide-extended polyols wherein the epoxylation index is sufficient toprevent a substantial degree of hydrolysis by pancreatic lipase;

It is another object of this invention to provide improved,substantially non-digestible fat substitutes or partial substitutes, ofesterified epoxide-extended polyols of the formula P(OH)_(a+c) (EPO)_(n)(FE)_(b) wherein the epoxylation index, n, is above about 2, andpreferably in the range of 2-8;

It is another object of this invention to provide improved fatsubstitutes which are peracylated epoxide-extended polyols in which thepolyols have 3-8 hydroxyl units;

It is another object of this invention to provide improved fatsubstitutes comprising acylated epoxide-extended glycerols wherein theepoxides are C₃ -C₆ epoxides;

It is another object of this invention to provide improved fatsubstitutes comprising acylated propylene oxide-extended glycerolswherein the propoxylation index, n, is above about 2, preferably in therange of 2-8;

It is another object of this invention to provide improved fatsubstitutes comprising esterified epoxide-extended polyols, andpreferably acylated propylene oxide extended glycerols in which the acylesters are C₈ -C₂₄ compounds and which have an in vitro pancreaticlipase hydrolysis index relative to olive oil of below about 10;

It is another object of this invention to provide acylatedepoxide-extended polyols in which the acyl groups are of sufficient sizeto prevett absorption through the walls of the digestive system, theepoxylation index is sufficiently high to prevent a substantial degreeof hydrolysis, and which have good organoleptic properties, and whichthemselves, and their hydrolysis products, are non-toxic;

It is another object of this invention to provide improved fatsubstitutes comprising triacylated polypropoxylated glycerols in whichthe propoxylation index is above about 2 and preferably about 5 or aboveand the acyl groups are C₈ -24 compounds, preferably C₁₄₋₁₈, and whichhave a lipase hydrolysis index of below about 10.

It is another object of this invention to provide methods of producingthe fat substitutes of this invention, and preferably which can usenaturally available oils such as soybean oil as the source of theglycerol and fatty acid moieties.

It is another object of this invention to provide improved foodcompositions and products employing the fat substitutes of thisinvention;

Still further and other objects will be evident from the specificationand claims of this application.

Summary

This invention comprises esterified epoxide-extended polyols (EEEPs),methods of preparation thereof, and their use as non-digestible fatsubstitutes (fat mimetics) having low-caloric food values, which havegood organoleptic characteristics, are substantially resistant tointestinal absorption, and do not appreciably hydrolyze in the digestivetract.

The structure of the non-digestible fat substitutes of this inventionmay be generally characterized as P(OH)a+c (EPO)_(n) (COOR)_(b), where:P(OH) is a polyol having a 2-8 primary hydroxyls and c=0-8 secondaryplus tertiary hydroxyls, with a+c being in the range of 3-8, EPO is a C₃-C₆ epoxide; n is the minimum epoxylation index average number having avalue generally equal to or greater than a and is a number sufficientthat greater than 95% of the primary hydroxyls of the polyol areconverted to secondary or tertiary hydroxyls; and RCOOH is a fatty acidacyl moiety in which R is an alkyl chain of 7 or more carbons, RCOOHpreferably being C₈ -24, and b is an average number in the range of 2<b≦(a+c).

Suitable polyols include sugars, glycerides or saccharides which arereacted (etherified) with C₃ -C₆ epoxides such as propylene oxide,butylene oxide, isobutylene oxide, pentene oxide, and the like toproduce epoxide-extended polyols (EEPs) having an epoxylation indexminimum of 2, and generally in the range of 2-8. Sugars may be selectedfrom glucose, mannose, galactose, arabinose, xylose, sorbitose, amylose,and the like.

We prefer the triol glycerol, with the resultant formula being: ##STR1##where d+e+f=n as defined above, x+y+z=b as defined above, R₁ =R₂ =H, R₃=H or alkyl, R₄ =alkyl, and R₅ =C₇₋₂₃, preferably C₁₃₋₁₇. Wherepropylene oxide is employed as the epoxide R₁, R₂ and R₃ are H, R₄ isMe, and d+e+f, the epoxylation (propoxylation) index, is 2-8, preferablyabout 3-5, based on in vitro pancreatic lipase activity relative toolive oil.

The epoxylation index is sufficiently high that the resultant EEEPs areresistant to digestive tract absorption and in vivo digestion bynon-specific digestive or lingual lipases. There are two factors to beconsidered. The first is the epoxylation index for non-digestability,the second is acyl chain length for non-absorption. Where n=4 is foundto be the suitable in vivo threshold for non-digestability, then thecutoff of the R₅ acyl chain length for direct absorption could be as lowas C₇ (the octanoate ester). This species (using glycerol and propyleneoxide) would have an average MW of 702, but since there is a MWdistribution in the mixture, species of MW of 586 and 644 would bepresent.

The esters of tertiary alcohols (R₃ =R₄ =alkyl) or secondary alcoholswith bulky substituents can provide good protection from lipasehydrolysis. For example: 1,2-epoxybutane (R₄ =Et), 2,3-epoxybutane (R₂=R₄ =Me), both butylene oxide; 1,2-epoxy-3-methylpropane (R₃ =R₄ =Me),isobutylene oxide; 1,2-epoxycyclohexane; and the like, may be used.

It should be understood that the epoxylation index encompasses themixtures produced by the base catalyzed reaction of the polyol with theepoxide. Thus, where glycerol and propylene oxide are used with C₁₆ -C₁₈fatty acids, we have found that as compared to olive oil as arepresentative substrate having a rate of in vitro lipase reactivity of100, the propoxylation index of 2 or greater has a hydrolysis rate valueon the order of 20-30% of the olive oil. By non-digestability we mean arate below about 20%, preferably 10%. Thus, food products could be madeor cooked in a mixture of natural fats and the synthetic fat mimetics ofthis invention blended in proportion to provide any predetermined amountof fat caloric value. Where n is 4-5, the relative lipase rate is zero.Depending on the organoleptic qualities desired, the amount ofsubstitution would range from a few percent, to give fractionalreduction in caloric value, to entire substitution for a non-caloricproduct. Conversely, where the EEEP product has a relative lipase rateclose to 20, different amounts of the EEEP fat substitute of thisinvention could be used in the blend to achieve a desired organolepticquality or provide a particular cooking use, (e.g., oil vs. fat).

Thus, in accord with this invention, in a low calorie food compositioncontaining fat-type organoleptic ingredients and non-fat ingredients,from about 10 to 100% of the total fat-type ingredients may comprise atleast one EEEP of this invention. In this regard, the feeding studies inExample 3 below illustrate formulations having 2.5% by weight of n=2.2and n=5 EEEP synthetic fat mimetics of this invention.

For example, in the case of glycerol and propylene oxide where a =2,c=1, n=2 and b=3, the resulting principal compound istriacyl-1,3-di-(2-hydroxypropyl) glycerol: ##STR2## Conversely, wheren=a, e.g., n=3 or more for glycerol, the EEEP compounds of thisinvention will include polyepoxides in the expoxide-extended interlinkbetween the polyol and the acyl ester moieties. Thus, for propyleneoxide, there will be present ##STR3## where f is 2 or more. The latterlinkages predominate. While we do not wish to be bound by theory, webelieve that thennon-digestibility of the EEEPs of this invention is dueto the alcohol ester linkage being secondary rather than primary.

Acylation with one or more C₈ -24 fatty acids produce an end productester with physical properties ranging from a liquid oil, through fatsand greases, and ultimately to waxes. The resultant EEEPs are useful infood formulations and for cooking as they have good mouth feel andcharacteristics similar to vegetable oils and fats. Being relativelynon-absorbable, non-digestible, and non-toxic they may be substitutedfor natural or processed oils and fats, but have no caloric value.

Examples of such fatty acids are caprylic, capric, lauric, myristic,myristoleic, stearic, palmitic, palmitoleic, rincinoleic, linoleic,linolenic, eleaostearic, arachidic, behenic, erucic, oleic, and/orheptadecanoic acid. The fatty acids can be derived from suitablenaturally occurring or synthetic fatty acids and can be saturated orunsaturated, including positional and geometric isomers, depending onthe desired physical properties, e.g., liquid or solid, of the fatcompound.

Fatty acids per se or naturally occurring fats and oils can serve as thesource for the fatty acid component. For example, rapeseed oil providesa good source for C₂₂ fatty acid. C₁₆ -C₁₈ fatty acids can be providedby tallow, soybean oil, or cottonseed oil. Shorter chain fatty acids canbe provided by coconut, palm kernel oil, or babassu oils. Corn oil, fishoil, lard, olive oil, palm oil, peanut oil, safflower seed oil, sesameseed oil, jojoba oil and sunflower seed oil, are examples of othernatural oils which can serve as the source of the fatty acid component.Among the fatty acids, those that are preferred have from about 14 toabout 18 carbon atoms, and are most preferably selected from the groupconsisting of myristic, palmitic, stearic, oleic, and linoleic. Thepreferred sources for the fatty acid components are natural fats andoils which have a high content of these fatty acids, e.g., soybean oil,olive oil, cottonseed oil, corn oil, tallow and lard.

Best mode examples of the invention include acylated propoxylatedglycerol compound mixtures (APGs) of the formula [G(PO)_(n) (FE)_(b) ],where G is glycerol (i.e. a=2 and c=1 in the P(OH)a+c formula above), POis Propylene Oxide, FE is a fatty acid ester moiety, the averagepropoxylation number n is in the range of 2-5, and b is an averagenumber between above 2 and 3. Suitable fatty acids include mixtures ofpalmitic acid or heptadecanoic acid with oleic acid. These APGs areresistant to hydrolysis by porcine pancreatic lipase, the dominantenzyme in fat digestion, in vitro.

Even where the fatty acid moieties are hydrolyzed off the EEEPs and APGsof this invention, no outward sign of toxicity of the resulting EEP wasobserved in our study. Indeed, even propylene glycol which would bereleased on cleavage of the EEP ether linkage is given GRAS (GenerallyRecognized as Safe) status by the FDA. Propylene glycol and itsderivatives are used at low levels in the food industry, e.g. assolvents for flavors and pharmaceuticals, and in baked goods, saladdressings and sauces.

The process of this invention involves a base (preferably alkali metal)catalyzed reaction of the polyol with the epoxide. As noted in theGibson and Quick paper, supra, the base catalysis opens the oxirane ringof the propylene oxide in the addition reaction to provide apredominance of secondary hydroxyl groups, on the order of 98% secondaryto 2% primary. We prefer, in the case of glycerol, to start with a fatsuch as soybean oil, split it to form glycerol and RCO₂ H, and separatethe glycerol from the fatty acid. This provides the glycerol for thebase catalyzed propoxylation addition reaction. The resultant G(PO)n,preferably n=2-5, is then reacted rapidly at high temperature, betweenabout 100 to 200° C., in the presence of paratoluene sulphonic acid(PTSA) with a stoichiometric amount of the soybean oil fatty acid toproduce the resultant APGs mixture product. The APGs product can berefined and bleached in a conventional manner, e.g. with alkali andclay, to provide a clean product of low color and low acid value.

DETAILED DESCRIPTION OF THE BEST MODE

The following detailed description is by way of example, not by way oflimitation, of the principles of the invention to illustrate the bestmode of carrying out the invention.

In this example, the epoxide (EPO) is represented by propylene oxide(PO), the polyol P(OH)a+c by glycerol (G), and the esterified fatty acidacyl moiety (FE) by a mixture of either palmitic or heptadecanoic acidswith oleic acid, to produce a food oil/fat substitute/mimetic of theformula [G(PO)n(FE)b], where n=2-5 and b=3. With the addition of 5 POunits, all the original polyol (in this example a triol) hydroxyls willhave been etherified (in this example propoxylated).

EXAMPLE 1 I. Propoxylated Glycerol Synthesis A. Catalyst Preparation

A catalyst solution for the propoxylation reaction is prepared toprovide 0.25 wt % K+in 6000 gms final propoxylated product. To preparethe catalyst, 27.59 grams powdered potassium hydroxide and 300 gramsglycerol, G, are charged to a 1000 cc rotary evaporation flask andheated under nitrogen at 75-80° C. with stirring for about one hour. Thecatalyst goes into solution leaving a cloudy product which is strippedon a rotary evaporator at 60-70° C./5mm Hg for one hour to remove water.The theoretical water loss is 12.98 grams. The catalyst solution (314.62gms) is added to a dry, nitrogen flushed 2-gallon stainless steelstirred reactor.

B. Proopxylation Reaction; 1:3 G:PO

To prepare propoxylated glycerol with three oxypropylene units theinitial glycerol charge is 2073.32 gms (i.e., 1773.32 gms charged asfree glycerol, and 300 gms added with the catalyst charge). Theremaining 1773.32 gms glycerol (MW =92.1 gm/mole) was added to thereactor under a continuous purge with dry nitrogen. The reactor washeated to 70-75° C. and nitrogen pressure was adjusted to 20 psig. Aninitial charge of 500 grams propylene oxide, PO, (MW 58.08 gm/mole) wasadded to the reactor, and the reaction exotherm was allowed to carry thetemperature up to 90° C. After the reaction was initiated, thetemperature was adjusted to 90-95° C. and the remaining dry propyleneoxide was added on a pressure demand basis over an 18 hour period. Apressure demand control valve system was used to control the additionrate. A reference pressure was set at 60 psig. If the reactor pressuredropped below this pressure he control valve opened and more propyleneoxide was charged to the reactor. When the pressure increased to greaterthan 60 psig, the valve closed. The propylene oxide was contained in ayoke that was suspended on a weight load cell, thereby permitting thecharging of the correct amount of propylene oxide. To preparepropoxylated glycerol with three oxypropylene units the total propyleneoxide charge is 3926.68 grams. Since the yoke had a 80 psig nitrogenpressure head, the overall reactor pressure increased to 80 psig whenall the propylene oxide was pushed out of the load cell yoke into thereactor. After all the propylene oxide had been added, the reactionmixture was allowed to cook out for an additional 4-6 hours to insurecomplete reaction.

When the reaction was complete, the product was removed hot from thereactor and was treated with Magnesol® (4 grams per 250 grams product)for two hours at 100-110° C. in order to remove the K+catalyst. Theresulting product was vacuum filtered through a Cellite® (purifieddiatomaceous silica) bed at 60-80° C. to provide the pure oligomericpolyol. Hydroxyl Number, VPO molecular weight, Gel PermeationChromatography (GPC) analysis, and ¹³ CNMR were used to characterize thehydroxy propoxylated glycerols mixture, HPGs. For the HPGs with threeoxypropylene units, polydispersity by GPC analysis is 1.19 and themolecular weight calculated from the Hydroxyl Number is 266 gms/mole.

II. Synthesis of APGs (Tri-acylated HPGs)

In a typical synthesis, a solution of 0.035 moles of redistilled acylchlorides (a mixture of a 1:5 molar ratio of either palmitoyl orheptadecanoyl chloride to oleoyl chloride) in dry chloroform (20 ml) isadded dropwise to a stirred solution of 0.01 mole of the HPGs in drychloroform (20 ml) and dry pyridine (6 ml). The addition is made at roomtemperature, under an atmosphere of dry nitrogen, and stirring iscontinued for a further 24 hours. A phase separation occurs in thereaction vessel. At the end of the reaction, the mixture is added towater (500 ml) and extracted several times with petroleum ether (3×500ml). The combined organic phase is then washed with water (2×500 ml),dilute aqueous HCl (2×500 ml), water (2×500 ml) aqueous potassiumbicarbonate (2×500 ml), and then water (2×500 ml), and dried overanhydrous sodium sulphate before evaporation of the solvent. Prior tocolumn chromatography, any free fatty acids still present are methylatedwith ethereal diazomethane. The crude acylated propoxylated glycerolmixtures (APGs) product is purified by passage down a silicic acidcolumn, eluting with a gradient of diethylether (0 to 100%) in petroleumether. Overall yields for the APGs synthesis fall in the range of59-75%. Purity and structure of the APGs product are confirmed by IR and¹ H NMR spectroscopy, and by Thin Layer Chromatography (TLC).

The resultant APG products are all oils at room temperature andgenerally a very acceptable pale yellow color, but which can be easilybleached or clarified by passing through charcoal. The APGs exhibitedreverse viscosity, with the n=1 and n=2.2 products (see Example 2 below)being slightly more viscous than olive oil, and the n=5 and n=8 productsslightly less viscous than olive oil. Similarly the n=5 and n=8 did notsolidify at 5° C. while the n 1 and n 2.2 exhibited partialcrystallization at 5° C. The molecular weight ranges are determined asfollows: n 1, 884-1000; n=2.2, 942-1116; n=5, 1058-1290; and n=8,1058-1348 assuming the trioleoyl derivatives and including 95% of thetotal mass of the polymeric mixtures. All exhibited organolepticallyacceptable properties, having a bland oily mouth feel without beingslimy.

EXAMPLE 2 III. In Vitro Testing of the APGs (n=1-8) for Digestion byPancreatic Lipase

Following the above procedure in Example 1, a number of APG products ofthe EEEPs of this invention were prepared in which n was varied in therange of from 1-8 by control of the amount of PO in the reaction. 100 mgof t he APG fat or oil of the invention to be tested is added to 10 mlof buffer containing 1 mM NaCl, 1 mM CaCl₂, 3 mM deoxycholate, 2 mMtris, and 10 g/1 of gum arabic. The mixture is vigorously shaken in acapped test-tube, and the emulsion is transferred to the pH statreaction vessel. The pH is titrated to 8.0 using a Radiometer pH stat(comprising a TTA80 titration assembly, a TTT80 titrator, and ABU80autoburette and a pHM82 pH meter). Porcine pancreatic lipase (0.1 ml,equivalent to 1000 units of enzyme, at pH 8.0) is added, the pH rapidlyre-equilibrated to 8.0, and then the reaction followed over a 20 minuteperiod by autotitration with 50 mM aqueous NaOH. The initial, linearrate is reported as micro moles of NaOH per hour required to keep the pHconstant by neutralizing the free fatty acids released by the action ofpancreatic lipase.

The results are given below in Table I, expressed as an average of 4determinations, relative to olive oil as a control (100%), where the EPOis PO and the FE is as in Example I, part II.

                  TABLE I                                                         ______________________________________                                        Digestibility (Lipase Activity)                                               Substrate       Realtive Rate*                                                ______________________________________                                        Control: Olive Oil                                                                            100                                                           Invention APGs:                                                               G(EPO).sub.n (FE).sub.b                                                       n = 0           76.2                                                          n = 1           46.2                                                          n = 2.2         18.9                                                          n = 5           0                                                             n = 8           0                                                             ______________________________________                                         *Average of four determinations.                                         

Based on the above Table I data, at n=3 the lipase hydrolysis rate isabout 10%, and at n=4 it is about 5%. We prefer the lipase hydrolysisrate to be below about 10%.

The corresponding acetate adducts of the tested APGs of Table I(n=1,2.2, 5 and 8) were assayed by Gas Liquid Chromatography (packedcolumn) to show the distribution of polypropylene oxide units in each.The results are shown in Table II:

                                      TABLE II                                    __________________________________________________________________________    Distribution of Polyepoxide Units                                             % Area by GLC (Packed Column)                                                            G:PO                                                               Adduct                                                                             PG G  1:1                                                                              1:2                                                                              1:3                                                                              1:4                                                                              1:5                                                                              1:6                                                                              1:7                                                                              1:8                                                                             1:9                                                                             1:10                                      __________________________________________________________________________    G(PO).sub.1                                                                        ND 31.1                                                                             46.2                                                                             19.9                                                                             2.7                                                          G(PO).sub.2.2                                                                      ND 2.1                                                                              22.7                                                                             40.5                                                                             28.0                                                                             5.9                                                                              0.7                                                    G(PO).sub.5                                                                        t  ND ND 1.4                                                                              16.1                                                                             34.5                                                                             28.5                                                                             13.6                                                                             5.1                                                                              0.8                                           G(PO).sub.8                                                                        t  ND ND ND 4.9                                                                              13.3                                                                             22.3                                                                             25.8                                                                             22.6                                                                             8.3                                                                             2.7                                                                             ND                                        __________________________________________________________________________     ND = Not detectable                                                           t = trace                                                                     PG = propyleneglycol                                                          G = glycol                                                               

The above components represent 90% of the mass trace integral, exceptfor G(PO)8 where the value was 67.8% due to presence of unknownadditional components, (NOT triacetin). The area % not corrected to givemass or mole % (FID response factors unknown).

Where the APGs product average molecular weight is too low, below about600-900, it is not useful as a non-digestible fat substitute because itwill be directly absorbed in the gut. We believe the non-digestibilityof the APGs product of this invention is due primarily to the presenceof secondary alcohol ester linkages.

EXAMPLE 3 FEEDING STUDIES IV. IN VIVO Testing

Sprague-Dawley weanling rats (male) were fed a laboratory chow dietcontaining 2.5% by weight of two different test compounds: either then=2.2 composition or the n=5 composition of Example 2, each containing18% of heptadecanoic acid as a marker, the balance of the fatty acid(acyl) moiety in the EEEP test compound being oleic acid. Total dietarylipid was kept at 10% (by weight) with 2.75% added corn oil, thelaboratory chow already containing 4.5% lipid. Also, a knownnon-digestible marker compound, 1,2-didodecyl-3-hexadecyl glycerol, wasadded to the diets at 0.25% (by weight) level.

The feeding trial continued for three weeks, during which time rat bodyweight gain increased at a rate equal to that of control animals. Nooutward signs of toxicity were observed. Feces were collected andanalysed for lipid content, using a GLC method based on heptadecanoicacid and 1,2-didodecyl-3-hexadecylglycerol markers. The data show thefollowing percentage recoveries of heptadecanoic acid (HDA) in thefeces:

                  TABLE III                                                       ______________________________________                                        Non-Digestability                                                                         % HDA as               Total                                                  Free Fatty  % HDA Still                                                                              Fecal                                      Test Compounds                                                                            Acid        Esterified HDA %                                      ______________________________________                                        n = 2.2     12          6          18                                         n = 5       13          31         44                                         ______________________________________                                    

The percentages listed under %HDA as Free Fatty Acids represents thepercentage of the test compound that was not absorbed, but the HDAmoiety of which was hydrolyzed in the gut or in the feces by digestiveenzymes or microbial action. The percentages listed under %HDA StillEsterified indicate the percentage still in original form, nothydrolyzed in gut or feces. The last column shows the total of the twopreceeding columns, being the percentage not absorbed or digested.

The data show that the test compounds, particularly the n=5 compounds(pentahydroxypropylglycerol), are suitably resistant to overalldigestion, which includes hydrolysis and absorption in the upperintestine of the rat, and some hydrolysis and utilization by themicrobial population of the cecum, colon, and feces.

The synthesis above involving propylene oxide can be employed forepoxylation with butylene oxide and isobutylene oxide, to produce thecorresponding epoxide extended polyols which are then acylated,preferably peracylated as above-described.

It should be understood that various modifications within the scope ofthis invention can be made by one of ordinary skill in the art withoutdeparting from the spirit thereof. We therefore wish our invention to bedefined by the scope of the appended claims as broadly as the prior artwill permit, and in view of this specification if need be.

We claim:
 1. A low calorie food composition containing fat-typeorganoleptic ingredient and non-fat ingredients, wherein from about 10to 100% of the total fat-type ingredients comprise at least oneepoxide-extended polyol ester of the formula P(OH)_(a+c) (EPO)n(COOR)bwhere P(OH) is a polyol having a=2-8 primary hydroxyls, c=0-8 secondaryplus tertiary hydroxyls, a+c is in the range of 3-8, EPO is a C_(3-C) ₆epoxide, n is a minimum epoxylation index average number n ≧a sufficientthat greater than 95% of the primary hydroxyls of said polyol areconverted to secondary or tertiary hydroxyls, COOR is a fatty acid acylmoiety in which R is a C_(7-C) ₂₃ alkyl chain, and b is an averagenumber in the range of 2<b ≦a+c, (EPO)_(n) forming polyepoxide interlinkbetween said polyol and said acyl ester moiety.
 2. A food composition asin claim 1 wherein n is sufficient to impart a lipase hydrolysis rate ofbelow about 10% compared to olive oil.
 3. A food composition as in claim2 wherein R is of sufficient length to be substantially resistant todigestive tract absorption.
 4. A food composition as in claim 3 whereinthe polyol is selected from the group consisting of sugars, glycerides,saccharides and mixtures thereof.
 5. A food composition as in claim 4wherein the epoxide is selected from the group consisting of propyleneoxide, pentene oxide, 1,2-epoxybutane, 2,3-epoxybutane,1,2-epoxy-2-methylpropane, 1,2-epoxycyclohexane, and mixtures thereof.6. A food composition as in claim 1 wherein P(OH) is glycrol, a is 2, cis 1, EPO is propylene oxide, n has an average value between about 2 to8, and b has an average value between above 2, to
 3. 7. A foodcomposition as in claim 6 wherein n is in the range of about 2-5 and bis
 3. 8. A food composition as in claim 7 wherein n is in the range ofabout 3-5.
 9. A food composition as in claim 1 wherein P(OH) isglycerol, a is 2, c is 1, EPO is selected from the group consisting ofbutylene oxide and isobutylene oxide, n has an average value betweenabout 2 to 8, and b has an average value between above 2, to
 3. 10. Afood composition as in claim 9 wherein n is in the range of about 2 to 5and b is
 3. 11. A food composition as in claim 10 wherein n is in therange of about 3 to
 5. 12. A low calorie food composition containingfat-type organoleptic ingredients and non-fat ingredients, wherein fromabout 10 to 100% of the total fat-type ingredients comprise at least oneepoxide-extended polyol ester of the formula P(OH)_(a+c) (EPO)_(n)(COOR)_(b) where P(OH) is glycerol, EPO is propylene oxide, n is anepoxylation index average value between about 2 to 8 and sufficient thatgreater than 95% of the primary hydroxyls of said polyol are convertedto secondary or tetiary hydroxyls, COOR is a fatty acid acyl moiety inwhich R is a C₇₋₂₃ alkyl chain, and b has an average value between above2, to 3 (EPO)_(n) forming a polypropylene oxide interlink between saidglycerol and said acyl ester moiety.
 13. A low calorie food compositioncontaining fat-type organoleptic ingredients and non-fat ingredients,wherein at least a portion of the total fat-type ingredients comprise atleast one epoxide-extended polyol ester of the formula P(OH)_(a+c)(EPO)_(n) (COOR)_(b) where P(OH) is a polyol having a=2-8 primaryhydroxyls, c=0-8 secondary plus tertiary hydroxyls, a+c is in the rangeof 3-7, EPO is a C_(3-C) ₆ epoxide, n is a minimum epoxylation indexaverage number n≧ a sufficient that greater than 95% of the primaryhydroxyls of said polyol are converted to secondary or tertiaryhydroxyls, COOR is a fatty acid acyl moiety in which R is a C_(7-C) ₂₃alkyl chain, and b is an average number in the range of 2<b ≧a+c,(EPO)_(n) forming a polyepoxide interlink between said polyol and saidacyl ester moiety, said portion of said fat-type ingredients comprisingsaid epoxide-extended polyol ester being selected to provide apredetermined amount of fat caloric value.